The present invention relates to the design of masonry drill bits which are especially adapted for drilling masonry, stone, rock, concrete, cement, cinder block, and the like. In particular, the masonry drill bits have an improved insert geometry, insert orientation, and interface clearance for providing improved drill speed and penetration rate.
Masonry drill bits have been known and are commonly used for drilling holes in especially hard friable material such as masonry or stone. These drill bits are usually comprised of an elongated body or shank having a spiral groove or grooves formed along their length and having a diametrically extending straight groove on their leading end. A hard insert was provided in the straight groove and was held in place by soldering or brazing. The insert usually had sharp cutting edges on its leading end so that the drill bit might effectively be used in the hard masonry or stone material. The spiral groove provides a channel for the discharge of chips, particles, dust and other drilling debris loosened by the leading end of the drill bit during the drilling operation. The insert must be capable of resisting wear, fracture, and the abrasive action of the chips from the material being drilled, while the body of the drill bit must maintain sufficient strength in the presence of heat generated in use.
In the manufacture of prior art masonry drills, it has been the practice to make the drill bit body of a material such as steel and to mount the abrasion-resistant insert or cutting elements at the cutting end. The body of the drill bit was normally formed by conventional rolling, machining or grinding of the spiral thread in a blank or rod of suitable length. The straight groove for the mounting of the insert or cutting element was then machined in the leading end of the drill bit body, and the cutting element was placed and secured. The cutting element was formed of a hard material such as tungsten carbide and was usually anchored in place in the body of the drill bit by soldering or brazing it in Examples of prior art masonry drill bits are shown in the following U.S. Pat. Nos.: 4,314,616 issued to Rauckhorst et al.; 4,527,638 issued to Sanchez et al.; 4,579,180 issued to Peetz et al.; 4,605,347 issued to Jodock et al.; 4,984,944 issued to Pennington, Jr. et al.; 5,184,689 issued to Sheirer et al.; and 5,630,478 issued to Schimke.
FIGS. 7 and 8 illustrate a typical drill bit having an insert with improper orientation. The insert in the typical drill bit is oriented whereby its orientation angle is greater than the present invention. As a result, the debris removal during drilling is hindered, causing the drill speed and penetration rate to be decreased.
FIG. 9 illustrates a typical drill bit having inadequate interface clearance. The grooves of the drill are aligned having reduced interface clearance which hinders the debris from entering the grooves for its elimination. As a result, the drill speed and penetration rate is decreased.
None of the patents described above provides the present invention's important advantages associated with a drill bit having improved insert geometry, insert orientation, and interface clearance. Some of the advantages are reducing friction and heat; resisting wear, fractures, and abrasive action of the chips; increasing design life of the elements; and removing debris. As a result, the present invention's drill bit rotary speed and penetration rate is increased.